U.S. patent application number 12/847283 was filed with the patent office on 2011-11-17 for pvdf/pvc alloys for plenum cable applications.
Invention is credited to Qibo Jiang, Paul Kroushi.
Application Number | 20110281050 12/847283 |
Document ID | / |
Family ID | 44629465 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110281050 |
Kind Code |
A1 |
Jiang; Qibo ; et
al. |
November 17, 2011 |
PVDF/PVC ALLOYS FOR PLENUM CABLE APPLICATIONS
Abstract
A cable jacket includes an extruded polymer made from PVDF, PVC
and a compatibilizing agent, where a ratio of PVDF, PVC and a
compatibilizing agent is substantially 7:3:1.
Inventors: |
Jiang; Qibo; (Ephrata,
PA) ; Kroushi; Paul; (Lancaster, PA) |
Family ID: |
44629465 |
Appl. No.: |
12/847283 |
Filed: |
July 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61334020 |
May 12, 2010 |
|
|
|
Current U.S.
Class: |
428/36.6 |
Current CPC
Class: |
C08L 27/16 20130101;
G02B 6/4436 20130101; H01B 13/148 20130101; H01B 3/443 20130101;
C08L 73/00 20130101; C08L 27/06 20130101; Y10T 428/1379 20150115;
C08L 27/16 20130101 |
Class at
Publication: |
428/36.6 |
International
Class: |
B32B 27/30 20060101
B32B027/30; B32B 1/08 20060101 B32B001/08; H01B 7/17 20060101
H01B007/17 |
Claims
1. A cable jacket comprising: an extruded polymer made from PVDF,
PVC and a compatibilizing agent, wherein a ratio of PVDF, PVC and a
compatibilizing agent is substantially 7:3:1.
2. The cable jacket of claim 1 wherein the level of PVDF is
substantially 63.3%, the level of PVC is substantially 27.3%, and
the level of compatibilizing agent is substantially 9.1%.
3. The cable jacket of claim 1 wherein the ratio of PVDF, PVC, and
said compatibilizing agent is such that said polymer maintains a
Low Temperature Breaking value of <-10.degree. C. under ASTM D
746 testing.
4. The cable jacket of claim 1 wherein said polymer retains at
least 85% rating of strain at break, modulus and tensile rating
after 60 days in oil under UL Oil Res II testing.
5. The cable jacket of claim 1 wherein the extruded polymer is
extruded as tape.
6. The cable jacket of claim 5 wherein said tape exhibits a
strength and strain at break of at least at 2800 psi and 280%
respectively.
7. The cable jacket of claim 1, wherein said compatibilzing agent
is an E/nBA/CO=ethylene/n-butyl acrylate/carbon monoxide.
8. The cable jacket of claim 1, wherein said polymer has a smoke
evolution of substantially 500 TSR m.sup.2/m.sup.2 when tested as a
100 mm.times.100 mm.times.3 mm plaque in the cone calorimeter at a
heat flux of 100 kW/m.sup.2.
9. A cable jacket comprising: an extruded polymer made from PVDF,
PVC and an E/nBA/CO=ethylene/n-butyl acrylate/carbon monoxide
compatibilizing agent, wherein a ratio of PVDF, PVC and a
compatibilizing agent is substantially 7:3:1.
Description
RELATED APPLICATION
[0001] This application is related to and claims the benefit of
priority from U.S. Provisional Patent Application No. 61/334,020,
filed on May 12, 2010, the entirety of which is incorporated by
reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present arrangement relates to communication cables.
More particularly, the present arrangement relates to jacket
material for communication cables.
[0004] 2. Description of the Related Art
[0005] In the United States, plastics used in the construction of
plenum rated cables are regulated under the National Fire
Protection Association standard NFPA 90A: Standard for the
Installation of Air Conditioning and Ventilating Systems. Plenum
cable is jacketed with a fire retardant plastic jacket of either a
low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene
polymer (FEP). All materials intended for use on wire and cables to
be placed in plenum spaces are designed to meet rigorous fire
safety test standards in accordance with NFPA 262 and outlined in
NFPA 90A.
[0006] Polyvinylidene Fluoride, or PVDF is a highly non-reactive
and pure thermoplastic fluoropolymer. PVDF is a specialty plastic
material in the fluoropolymer family; it is used generally in
applications requiring the highest purity, strength, and resistance
to solvents, acids, bases and heat and low smoke generation during
a fire event. Compared to other fluoropolymers, it has an smoother
melt process because of its relatively low melting point of around
155.about.192.degree. C. However, PVDF has a significant cost
associated with it, making it less than ideal to use in its pure
form.
[0007] To mitigate costs, prior cables have used a PVDF/PVC alloy
composition for the jacket for both optical fiber and shielded data
cable products. The PVDF is blended with PVC (lower cost) in order
to reduce the cost of the finished compound while maintaining both
the good flame properties and the mechanical properties of the
PVDF. However, these PVDF/PVC alloys have problems with low
temperature performance in the range of sub 0.degree. C.
temperatures due to the incompatibility of the two polymers. For
example, the physical properties of the PVDF/PVC combination
polymer jacket are extremely sensitive to manufacturing process
variations, i.e. the two polymers do not weave/blend together, and
thus the resulting cable jacket fractures easily in low
temperatures. The prior art related to compatibilizers has not
effectively addressed compatibilizers intended for plenum cables
that have good low temperature performance.
[0008] Thus, although prior art plenum rated PVDF+PVC blends were
available approximately 10 years ago, they were notorious for
cracking at low temperatures. The present invention as claimed
combines excellent flame and smoke performance with excellent low
temperature properties.
OBJECTS AND SUMMARY
[0009] The present arrangement overcomes the drawbacks of the prior
art by using a compatibilizing agent to improve the compatibility
between the PVDF and PVC that results in an improved compatibility
between the PVDF and PVC and the resultant improved/maintained
physical properties, particularly with respect to cold temperature
resistance.
[0010] To this end, the present arrangement includes a cable jacket
comprising a ratio of PVDF, PVC and a compatibilizing agent where
the ratio is selected in order to obtain compatibility between the
PVDF and PVC while maintaining the physical properties necessary in
order to meet various testing standards.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention can be best understood through the
following description and accompanying drawings, wherein:
[0012] FIG. 1 shows a cable having a jacket in accordance with one
embodiment;
[0013] FIG. 2 illustrates cone calorimeter data regarding smoke
properties in accordance with one embodiment;
[0014] FIG. 3 is a chart comparing the low temperature brittleness
values in accordance with one embodiment; and
[0015] FIG. 4 is a chart illustrating the UL Oil Res II
(Underwriters Laboratory Oil Resistance Test II) testing results in
accordance with one embodiment.
DETAILED DESCRIPTION
[0016] FIG. 1 shows a typical LAN cable 10 having four twisted
pairs 12 and a jacket 14. Although the example is shown as a four
pair LAN cable, the same principles of the invention may be equally
applied to coating and jackets used for fiber or other types of
communication and power cables.
[0017] In one arrangement, jacket 14 of cable 10 is made from an
extruded PVDF/PVC mixture as described in more detail below.
[0018] PVDF is a Fluoropolymer with a low melting temperature,
.about.155.degree. C. or more, with outstanding flame and smoke
properties. Jacket 14 is ideally made of substantially PVDF with
some PVC and a compatibilizing agent added thereto. In one
exemplary arrangement, the respective amounts of the three
components are substantially in a ratio of 7:3:1; PVDF, PVC and
compatibilizing agent (by weight) as described in more detail
below.
[0019] The compatibilizing agent used to improve the compatibility
between the PVDF and PVC is preferably E/nBA/CO=ethylene/n-butyl
acrylate/carbon monoxide. For example, Du Pont.TM. Elvaloy.RTM.
HP661 is an exemplary ethylene terpolymer (E/nBA/CO,) which is most
commonly used as a modifier for a variety of other polymers. There
are different types of ELVALOY, which are often blended with other
polymers to modify their physical properties.
[0020] One use for ethylene terpolymer additives (such as ELVALOY)
is as solid plasticizers in PVC. However, in addition to being
compatible with PVC, the acrylate functionality present in the
ELVALOY helps compatibilize it with PVDF as well. Moreover, the
processing temperature of ELVALOY also falls within the range of
both PVDF and PVC.
[0021] According to the present arrangement, the PVDF/PVC alloy for
jacket 14 is made initially by blending pellets of all three
materials together on a two roll mill and extruding strips through
a single screw extruder. The combined PVDF, PVC, and Elvaloy
pellets are added in the correct proportions at the feed throat of
a twin screw compounding line. It is noted that this is one
exemplary process for making the PVDF/PVC/additive blend for jacket
14, however, other processes may be used as well.
[0022] In one arrangement several tests were performed in order to
optimize the relative levels of PVDF, PVC and the compatibilizing
additive, to obtain the best performance qualitatively and
economically while maintaining the processability of the
compositions.
[0023] FIG. 2 illustrates cone calorimeter data for a ratio of
PVDF/PVC/Compatibilizer (7:3:1) which indicates a reduction in
smoke with the PVDF/PVC/compatibilizer alloy (T5) versus the PVDF
alone (brand name Kynar 2950) at a heat flux of 100 kW/m.sup.2. In
this test, the evolution of 500 TSR m.sup.2/m.sup.2 (Total Smoke
Release) was tested for samples of 100 mm.times.100 mm.times.3 mm
plaque in the cone calorimeter at a heat flux of 100
kW/m.sup.2.
[0024] On the graph, the total smoke release (TSR) is graphed over
time (in seconds) for six different samples:
[0025] Kynar (PVDF)
[0026] AG X (PVC)
[0027] Present Samples (7:3:1 PVDF; PCV:comp)--one as pressed
plaque (TO), the other is an extruded tape (T5)
[0028] T0=63.6% Kynar 2950 PVDF+27.3% PolyOne L-6815 PVC+9.1%
DuPont Elvaloy HP 441
[0029] T5=63.6% Kynar 2950 PVDF+27.3% PolyOne L-6815 PVC+9.1%
DuPont Elvaloy HP 441
[0030] Other samples with more PVC than present sample:
[0031] T3=50% Kynar 2950 PVDF+35.5% PolyOne L-6815 PVC+9.1% DuPont
Elvaloy HP 441
[0032] T4=40% Kynar 2950 PVDF+45.0% PolyOne L-6815 PVC+15.0% DuPont
Elvaloy HP 441
[0033] Thus, simply adding PVC to PVDF alone does not automatically
result in better smoke properties than PVDF alone, but when the
present ratio and compatibilizer is used it shows a two fold
decrease.
[0034] Additionally, the composition of the present invention used
for jacket 14 was also subjected to elongation breaking tests in
the form of compression molded plaques. Tensile and elongation
tests were run on the extruded tape to measure the strain at break
and tensile strength. Strain at break refers to the elongation (in
percentage) before a break and tensile strength is the related
feature (in "PSI" Pounds Per/Square Inch) measuring the force
required to cause a tensile break. Reference is made to FIG. 3, and
tape T5, the present example, showing that the strength and strain
at break are maintained in a high level when the composition is
with the ratio of 7:3:1 among PVDF, PVC and E/nBA/CO.
[0035] As shown in FIG. 3, the two present examples, T0 and T5 (TO
using PVC L6815 and T5 using PVC X-1116) were able to achieve
greater than 300% percent elongation of the compounded plastic
sample before breaking. In other words, the plastic sample
stretched over three times its original length when tested per ASTM
D-638 testing standard before breaking.
[0036] Separately, as shown in FIG. 3 samples T0 and T5 were formed
again as extruded tape on a single screw extruder. In this case,
the strain at break for both samples still exceeded 280% (even
better 462% for sample T0).
[0037] Moreover, the ASTM D 746 low temperature brittleness value
obtained for T5 tape was -10.degree. C. The ASTM D-746 value
defines a procedure in which plastic sample of a certain geometry
is placed in a liquid bath at low temperatures. They are then
impacted by a quickly moving device at low temperatures. The
temperature at which half of the samples break is defined as the
brittleness temperature.
[0038] Generally, plenum rated cable jacket compounds with low
temperature brittleness values of >0.degree. C. are at a risk
for low temperature failures in the field while compounds with low
temperature brittleness values of <-10.degree. C. have a lower
risk of field failure. (Samples break in two when they fail the
test and pass when they remain intact) As seen in the final row and
column of FIG. 3, the LTB value for the primary present sample T5
is <-10.degree. C.
[0039] Although the other samples shown in FIG. 3, such, as T3 and
T4 also had good elongation breaking measurements under the same
tests, as noted above in relation to FIG. 2, they did not have the
advantageous total smoke release capabilities. Moreover, they did
not perform well in cold temperature testing and were not able to
achieve the low temperature rating of <-10.degree. C. that the
present composition (T5) could.
[0040] In another arrangement, referring to FIG. 4, UL Oil Res II
testing was conducted on the sample cable using the exemplary T5
extruded test tape compound for jacket 14 of the test cable 10
described above. The compound for jacket 14 met the requirements
for this severe oil resistance test by retaining at least 85% or
even improving strain at break, modulus and tensile resistance
after 60 days in oil. Typical PVC based plenum jacket compounds do
not meet this strict requirement.
[0041] While only certain features of the invention have been
illustrated and described herein, many modifications,
substitutions, changes or equivalents will now occur to those
skilled in the art. It is therefore, to be understood that this
application is intended to cover all such modifications and changes
that fall within the true spirit of the invention.
* * * * *